GMC Pickup C2500 (1985-2000) org/ Wiring diagrams

AUXILIARY LEAD (TAPED NEAR FUSE BLOCK) BLK WIRE BLU WIRE BRN WIRE CARGO CHMSL CARGO LAMP SWITCH CARGO/ CHMSL LAMPS CLEARANCE LAMPS CIRCUIT (W/DUAL REAR WHEELS) CONVENIENCE CENTER (BEHIND INTERIOR LEFT SIDE LIGHTS SYSTEM OF I/P) CONVENIENCE CENTER (BEHIND LEFT SIDE OF I/P) CRUISE CONTROL SYSTEM CTSY LPS DK BLU WIRE DK DK DK GRN WIRE FUSE 1 FUSE 16 FUSE 3 FUSE 9 FUSE BLOCK (LOWER LEFT SIDE OF I/P) GRN WIRE HAZARD HAZARD FLASHER HEADLIGHT/ PANEL DIMMER SWITCH HOT AT ALL TIMES HOT AT ALL TIMES U/H FUSE/ RELAY CENTER (LEFT REAR ENGINE COMPT) HOT IN RUN, BULB TEST OR START IDENTIFICATION LAMPS INSTRUMENT CLUSTER LEFT BACKUP LIGHT LEFT CLEAR- ANCE LAMP LEFT FRONT MARKER LIGHT LEFT FRONT PARK/ TURN LIGHTS LEFT TAIL/ STOP/ TURN LIGHT LEFT TURN IND LEFT TURN, HAZARD LH RH LICENSE LICENSE LIGHTS LIGHT LT BLU WIRE LT DK LT GRN WIRE LT LT M/T A/T MAXI FUSE 2 NORMAL ORG/ WIRE PARADE MODE SW PARK LPS PARK RHEO- STAT OFF PLATFORM HITCH GROUND PNK M/T A/T WIRE PNK WIRE PPL RED WIRE RIGHT BACKUP LIGHT RIGHT CLEAR- DK ANCE LAMP RIGHT FRONT MARKER LIGHT RIGHT FRONT PARK/ TURN LIGHTS RIGHT TAIL/ STOP/ TURN LIGHT RIGHT TURN IND RIGHT TURN, HAZARD STOP HAZ STOP LAMP RELAY STOP LAMP/ TCC SWITCH (ON BRAKE PEDAL SUPPORT BRACKET) TURN B/U TURN FLASHER TURN/ HAZARD SWITCH U/H FUSE/ RELAY CENTER (LEFT REAR ENGINE COMPT) W/ STEP W/O STEP BUMPER BUMPER W/OPTIONAL TRAILER TOW PACKAGE WHT WIRE WIRE LEADS ARE SPLICED TO TRAILER WIRING, OR CONNECTED TO TRAILER WIRE PLUG YEL WIRE

BLK WIRE BRN WIRE ENDGATE CLEARANCE LAMPS ENDGATE CROUND FUSE 9 FUSE BLOCK (LOWER LEFT SIDE OF I/P) HEADLIGHT/ PANEL DIMMER SWITCH HOT AT ALL TIMES LEFT FRONT CLEARANCE LAMP LEFT REAR CLEARANCE LAMP LEFT REAR FENDER OFF ORG/ WIRE PARADE MODE SW PARK PARK LPS RHEO- STAT RIGHT FRONT CLEARANCE LAMP RIGHT REAR CLEARANCE LAMP RIGHT REAR FENDER

BLK WIRE BLU WIRE BRN WIRE BULB CHECK FOG LTS ENABLE CONVENIENCE CENTER DAYTIME RUNNING LAMP INDICATOR INSTRUMENT CLUSTER DAYTIME RUNNING LAMPS MODULE (BEHIND LEFT SIDE OF I/P) DAYTIME RUNNING LAMPS RELAY (ENGINE COMPARTMENT FRONT PLENUM PANEL) DIODE DK BLU WIRE DK GRN/WHT WIRE FOG LAMP ON INDICATOR SOLID STATE SWITCH FOG LAMP RELAY FOG LAMP SWITCH GRN WIRE GRY WIRE HEAD PARK HEADLAMP DIMMER SWITCH HEADLIGHT SWITCH ASSEMBLY HI BEAM INDICATOR HI LO HOT AT ALL TIMES HOT AT ALL TIMES DRL-FOG FUSE 15 HOT IN RUN, BULB TEST OR START FUSE BLOCK GAUGES FUSE 4 ILLUM LAMP LAMP FEED HI BEAM FEED HI BEAM INDICATOR LEFT HIGH BEAM HEADLAMP LEFT LOW BEAM HEADLAMP LT GRN WIRE LT GRN/BLK WIRE OFF OFF HEAD ORG/ WIRE OUTPUT TO RELAY GROUND PARK PARK BRAKE WARNING SWITCH (AT PARK BRAKE, UNDER LEFT SIDE OF I/P) PICKUP EXT. CAB PNK IGNITION WIRE PNK WIRE PPL PPL LEFT FOG LAMP PPL RIGHT FOG LAMP RIGHT HIGH BEAM HEADLAMP RIGHT LOW BEAM HEADLAMP SUBURBAN PICKUP UTILITY EXT. CAB CREW CAB SUBURBAN UTILITY CREW CAB TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE

BLK WIRE BRN WIRE BULB CHECK FOG LTS ENABLE CONVENIENCE CENTER DAYTIME RUNNING LAMP INDICATOR INSTRUMENT CLUSTER DAYTIME RUNNING LAMPS MODULE (BEHIND LEFT SIDE OF I/P) DAYTIME RUNNING LAMPS RELAY (ENGINE COMPARTMENT FRONT PLENUM PANEL) DIODE DK BLU WIRE DK GRN/WHT WIRE FOG LAMP ON INDICATOR SOLID STATE SWITCH FOG LAMP RELAY FOG LAMP SWITCH GRN WIRE GRY WIRE HEAD PARK HEADLAMP DIMMER SWITCH HEADLIGHT SWITCH ASSEMBLY HI BEAM INDICATOR HI LO HOT AT ALL TIMES HOT AT ALL TIMES DRL-FOG FUSE 15 HOT IN RUN, BULB TEST OR START FUSE BLOCK GAUGES FUSE 4 ILLUM LAMP LAMP FEED HI BEAM FEED HI BEAM INDICATOR LEFT HEADLAMP ASSEMBLY HI LO LT GRN WIRE LT GRN/BLK WIRE OFF OFF HEAD ORG/ WIRE OUTPUT TO RELAY GROUND PARK PARK BRAKE WARNING SWITCH (AT PARK BRAKE, UNDER LEFT SIDE OF I/P) PICKUP EXT. CAB PNK IGNITION WIRE PNK WIRE PPL PPL LEFT FOG LAMP PPL RIGHT FOG LAMP RIGHT HEADLAMP ASSEMBLY HI LO SUBURBAN PICKUP UTILITY EXT. CAB CREW CAB SUBURBAN UTILITY CREW CAB TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE

BLK WIRE BLU WIRE BULB CHECK DAYTIME RUNNING LAMP INDICATOR DAYTIME RUNNING LAMPS MODULE (BEHIND LEFT SIDE OF I/P) DAYTIME RUNNING LAMPS RELAY (ENGINE COMPARTMENT FRONT PLENUM PANEL) DK BLU WIRE GRN WIRE HEAD PARK HEADLAMP DIMMER SWITCH HEADLIGHT SWITCH ASSEMBLY HI BEAM INDICATOR HOT AT ALL TIMES HOT AT ALL TIMES DRL-FOG FUSE 15 HOT IN RUN, BULB TEST OR START FUSE BLOCK GAUGES FUSE 4 INSTRUMENT CLUSTER LAMP FEED HI BEAM FEED HI BEAM INDICATOR LEFT HIGH BEAM HEADLAMP LEFT LOW BEAM HEADLAMP LT GRN WIRE LT GRN/BLK WIRE OFF OFF HEAD ORG/ WIRE OUTPUT TO RELAY GROUND PARK PARK BRAKE WARNING SWITCH (AT PARK BRAKE, UNDER LEFT SIDE OF I/P) PNK IGNITION 10 10 WIRE PNK WIRE RIGHT HIGH BEAM HEADLAMP RIGHT LOW BEAM HEADLAMP TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE

A/C SIG AIR CONDITIONING SYSTEM APP 3 SENS SIG FUEL TEMP SIG IAT SIG B/H BARO SENSOR (VIN F) (UPPER LEFT SIDE OF COWL) BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE ECM I FUSE EGR CONTROL PRESSURE/ BARO SENSOR (VIN P, S) (UPPER LEFT SIDE OF COWL) ENG-I FUSE FUEL HEATER (TOP REAR OF ENGINE) FUEL PUMP OIL PRESSURE SWITCH FUEL PUMP RELAY (RIGHT UPPER COWL) FUEL PUMP/SENDER (IN FUEL TANK) FUSE BLOCK FUSIBLE LINK FUSIBLE LINKS GAUGES FUSE GLOW PLUG CONTROL RELAY (RIGHT REAR TOP OF ENGINE) GLOW PLUG SIG GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT AT ALL TIMES STOP FUSE HOT IN RUN BRAKE FUSE HOT IN RUN, BULB TEST OR START HOT IN START OR RUN GLOW PLUG FUSE IGNITION FEED INSTRUMENT CLUSTER INSTRUMENT CLUSTERS SYSTEM LEFT BANK GLOW PLUGS LT BLU/BLK WIRE LT GRN WIRE MANIFOLD ABSOLUTE PRESSURE SENSOR (TURBO ONLY) (LEFT REAR ENGINE COMPT, AT COWL) ORG/ WIRE ORG/BLK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE RED WIRE RED/BLK WIRE RIGHT BANK GLOW PLUGS SERVICE ENGINE SOON LAMP TAN WIRE TAN/BLK WIRE TCC/ BRAKE SWITCH (ON BRAKE PEDAL SUPPORT BRACKET) VIN P ONLY WAIT LAMP "SERVICE THROTTLE" LAMP WASTEGATE SOL CTRL EGR VENT SOL CTRL "SERVICE THROTTLE" LAMP WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

11 12 PPL 2-3 SHIFT SOL CTRL FUEL INJ CTRL EGR SOL CTRL ENG SHUT-OFF CTRL 4 WHEEL DRIVE LOW SWITCH 983 474 PPL 999 998 961 452 PPL ACCELERATOR PEDAL POSITION (APP) MODULE (TOP OF ACCELERATOR BRACKET) ANTI-LOCK BRAKES SYSTEM APP 1 SENSOR ENGINE COOLANT TEMPERATURE (ECT) SENSOR (RIGHT SIDE OF ENGINE) APP 2 SENSOR APP 3 SENSOR B/H BATTERY FEED FWD LOW SW BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE CKP SIG OPTICAL SENS GND OPTICAL SENS CAM SIG CRANK FUSE TRANS FUSE CRUISE CONTROL SYSTEM CRUISE ON/OFF SIG DATA LINK CONNECTOR (UNDER LEFT SIDE OF I/P) DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM-B FUSE ELECTRONIC 4-SPEED AUTOMATIC OVERDRIVE TRANSMISSION ENGINE SHUT- OFF SOLENOID (TOP FRONT OF ENGINE) FUEL INJ CTRL FUEL SOL FUSE FUEL SOLENOID (TOP FRONT OF ENGINE) FUEL SOLENOID DRIVER (TOP FRONT OF ENGINE) FUSE FUSE BLOCK GLOW PLUG RLY CTRL SERIAL DATA TRANS OUTPUT SPD SIG GRY WIRE GRY/BLK WIRE HOT AT HOT IN RUN ALL TIMES HOT IN CRANK HOT IN START OR RUN LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE OPTICAL/ FUEL TEMP SENSOR (TOP FRONT OF ENGINE) ORG/ WIRE ORG/BLK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE PRESS CTRL SOL (LO) RANGE MODE SELECTOR RED WIRE RED/BLK WIRE RESUME/ACCEL SIG SET/COAST SIG SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) SYSTEM GND CLOSURE SIG APP 2 SENS GND APP 1 SENS GND APP 3 SENS GND SENSOR GND TAN WIRE TAN/BLK WIRE TAN/WHT WIRE TCC BRAKE SW TCC PWM SOL 3-2 SHIFT SOL 2-3 SHIFT SOL 1-2 SHIFT SOL TCC SOL TRANS FLUID TEMP (TFT) SENSOR TRANS OUTPUT VEHICLE SPEED SENSOR BUFFER (UNDER RIGHT END OF I/P) VIN P ONLY VSS VSS HI RESOLUTION SIG VSS INPUT VSS INPUT PRESSURE CONTROL SOL VSS OUTPUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

11 12 PPL A/C SIG AIR CONDITIONING SYSTEM APP 3 SENS SIG FUEL TEMP SIG IAT SIG B/H BARO SENSOR (VIN F) (UPPER LEFT SIDE OF COWL) BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE ECM I FUSE EGR CONTROL PRESSURE/ BARO SENSOR (VIN P, S) (UPPER LEFT SIDE OF COWL) ENG-I FUSE FUEL HEATER (TOP REAR OF ENGINE) FUEL PUMP OIL PRESSURE SWITCH FUEL PUMP RELAY (RIGHT UPPER COWL) FUEL PUMP/SENDER (IN FUEL TANK) FUSE BLOCK FUSIBLE LINK FUSIBLE LINKS GAUGES FUSE GLOW PLUG CONTROL RELAY (RIGHT REAR TOP OF ENGINE) GLOW PLUG SIG GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT AT ALL TIMES STOP FUSE HOT IN RUN BRAKE FUSE HOT IN RUN, BULB TEST OR START HOT IN START OR RUN GLOW PLUG FUSE IGNITION FEED 2-3 SHIFT SOL CTRL INSTRUMENT CLUSTER INSTRUMENT CLUSTERS SYSTEM LEFT BANK GLOW PLUGS LT BLU/BLK WIRE LT GRN WIRE MANIFOLD ABSOLUTE PRESSURE SENSOR (TURBO ONLY) (LEFT REAR ENGINE COMPT, AT COWL) ORG/ WIRE ORG/BLK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 RED WIRE RED/BLK WIRE RIGHT BANK GLOW PLUGS SERVICE ENGINE SOON LAMP TAN WIRE TAN/BLK WIRE TCC/ BRAKE SWITCH (ON BRAKE PEDAL SUPPORT BRACKET) VIN P ONLY WAIT LAMP "SERVICE THROTTLE" LAMP WASTEGATE SOL CTRL EGR VENT SOL CTRL "SERVICE THROTTLE" LAMP WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

1222 1224 1225 1226 PNK WIRE 2-3 SHIFT SOL CTRL FUEL INJ CTRL EGR SOL CTRL ENG SHUT-OFF CTRL 4 WHEEL DRIVE LOW SWITCH 983 474 PPL 999 998 961 452 PPL ACCELERATOR PEDAL POSITION (APP) MODULE (TOP OF ACCELERATOR BRACKET) ANTI-LOCK BRAKES SYSTEM APP 1 SENSOR ENGINE COOLANT TEMPERATURE (ECT) SENSOR (RIGHT SIDE OF ENGINE) APP 2 SENSOR APP 3 SENSOR B/H BATTERY FEED FWD LOW SW BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE CRANK FUSE TRANS FUSE CRUISE CONTROL SYSTEM CRUISE ON/OFF SIG DATA LINK CONNECTOR (UNDER LEFT SIDE OF I/P) DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM-B FUSE ELECTRONIC 4-SPEED AUTOMATIC OVERDRIVE TRANSMISSION ENGINE SHUT- OFF SOLENOID (TOP FRONT OF ENGINE) FUEL INJ CTRL FUEL SOL FUSE FUEL SOLENOID (TOP FRONT OF ENGINE) FUEL SOLENOID DRIVER (TOP FRONT OF ENGINE) FUSE FUSE BLOCK GRY WIRE GRY/BLK WIRE GRY/RED WIRE HOT AT ALL TIMES HOT IN CRANK HOT IN RUN HOT IN START OR RUN LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE OPTICAL SENSOR AND FUEL TEMPER- ATURE SENSOR (TOP FRONT OF ENGINE) ORG/ WIRE ORG/BLK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE PRESSURE CONTROL SOL RANGE MODE SELECTOR RED WIRE RED/BLK WIRE RESUME/ACCEL SIG SET/COAST SIG SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) SYSTEM GND CLOSURE SIG APP 2 SENS GND APP 1 SENS GND APP 3 SENS GND SENSOR GND TAN WIRE TAN/WHT WIRE TCC BRAKE SW TCC SOL 2-3 SHIFT SOL 1-2 SHIFT SOL TRANS FLUID TEMP (TFT) SENSOR TRANS INPUT SPD SIG CKP SIG OPTICAL SENS GND OPTICAL SENS CAM SIG TRANS OUTPUT TRANSMISSION INPUT SPEED SENSOR VEHICLE SPEED SENSOR BUFFER (UNDER RIGHT END OF I/P) VIN P ONLY VSS VSS HI RESOLUTION SIG VSS INPUT VSS OUTPUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

A/C SIG AIR CONDITIONING SYSTEM APP 3 SENS SIG FUEL TEMP SIG IAT SIG B/H BARO SENSOR (VIN F) (UPPER LEFT SIDE OF COWL) BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE ECM I FUSE EGR CONTROL PRESSURE/ BARO SENSOR (VIN P, S) (UPPER LEFT SIDE OF COWL) ENG-I FUSE FUEL HEATER (TOP REAR OF ENGINE) FUEL PUMP OIL PRESSURE SWITCH FUEL PUMP RELAY (RIGHT UPPER COWL) FUEL PUMP/SENDER (IN FUEL TANK) FUSE BLOCK FUSIBLE LINK FUSIBLE LINKS GAUGES FUSE GLOW PLUG CONTROL RELAY (RIGHT REAR TOP OF ENGINE) GLOW PLUG SIG GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT AT ALL TIMES STOP FUSE HOT IN RUN BRAKE FUSE HOT IN RUN, BULB TEST OR START HOT IN START OR RUN GLOW PLUG FUSE IGNITION FEED INSTRUMENT CLUSTER INSTRUMENT CLUSTERS SYSTEM LEFT BANK GLOW PLUGS LT BLU/BLK WIRE LT GRN WIRE MANIFOLD ABSOLUTE PRESSURE SENSOR (TURBO ONLY) (LEFT REAR ENGINE COMPT, AT COWL) ORG/ WIRE ORG/BLK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE RED WIRE RED/BLK WIRE RIGHT BANK GLOW PLUGS SERVICE ENGINE SOON LAMP TAN WIRE TAN/BLK WIRE TCC/ BRAKE SWITCH (ON BRAKE PEDAL SUPPORT BRACKET) VIN P ONLY WAIT LAMP "SERVICE THROTTLE" LAMP WASTEGATE SOL CTRL EGR VENT SOL CTRL "SERVICE THROTTLE" LAMP WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE